Hi lawrencelyl and Eliovp,

I did many tests today- but still the same issue. First of all, you are right, lawrencelyl, this situation is even there with the stock bios. So it's not a mod issue.

I've been running tests today by running it in win7,win8 and win10. all clean installs. driver left and right. I now doubt it's a driver issue.
When core clock increase, the system gets very unstable. As mentioned, nano crashes when I increase the core clock from 800 to 900. I even tried to increase the core clock by 50mV.

@lawrencelyl : Can you run the bios mod with monitor plugged in? What are your settings in afterburner and which mem clock mod are you running? Are you on XFX?

At the beginning I thought it's due to the monitor. Or could it be another issue?
Eliovp, would a snapshot of my stock bios somehow help you to see if we now have a fundamental difference? Let me know.
I'll run some more tests next week, but not many ideas left what to try...

Cheers,
Talan